JPH08336246A - Rotor with permanent magnet - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a rotor with a permanent magnet that can reduce iron loss by alleviating the concentration of magnetic flux at a specific location. A rotor 3 in which a plurality of pairs of permanent magnets 8a, 8b are embedded in a rotor body 3a made of a high-permeability material at intervals of two layers or more per pole in the rotor radial direction.
In, the distance between the permanent magnets 8a and 8b in the layer relation is
It is characterized in that the gap 3b on the side of the end portions 9a, 9b located at least on the forward side in the rotation direction of the rotor 3 is wider than the gap on the other portions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotor with a permanent magnet in a motor which utilizes not only magnet torque but also reluctance torque.

[0002]

2. Description of the Related Art Conventionally, there is known a rotor in which a permanent magnet of one layer is embedded in a rotor body made of a material having a high magnetic permeability such as iron. However, from the viewpoint of effectively utilizing the reluctance torque, the above-mentioned conventional example is not preferable, and the present inventors have developed a rotor with a two-layer structure as shown in FIG. 4 in order to solve the problem. Patent application (Japanese Patent Application No. 7-134023).

The rotor 3 according to this prior invention is constructed by embedding four sets of permanent magnets 8a, 8b ... In a rotor body 3a made of iron, which are arranged in two layers at intervals in the radial direction of the rotor. The permanent magnets 8a and 8b of each set are arranged adjacent to each other so that the S poles and the N poles are alternately arranged, and the permanent magnets 8a and 8b having a two-layer relationship have the same polarity on the outer peripheral side. Has been done. Each of the outer permanent magnets 8a, ... And the inner permanent magnets 8b, ... Is formed in an arc shape that is convex in the centripetal direction of the rotor, and has an outer permanent magnet 8a and an inner side that are in a two-layer relationship. The permanent magnets 8b are arranged in parallel with each other, and the distance between them is constant.

As described above, the rotor 3 in which the permanent magnets 8a located on the outer peripheral side of the rotor and the permanent magnets 8b located on the inner peripheral side of the rotor are embedded in two layers with a gap therebetween, is a group of windings 10 on the stator 2 side. And the permanent magnet 8 (8
a, 8b) and a reluctance torque generated by a magnetic path generated by the rotating magnetic field being formed on the surface side of the rotor main body 3a or in a space between the inner and outer permanent magnets 8b, 8a. It rotates with the combined torque of.

[0005]

In the structure of the prior invention described above, the combined magnetic flux of the magnetic flux generated by the permanent magnet embedded in the rotor body and the magnetic flux generated by the winding on the stator side will be described below. The rotation direction R of the rotor 3
Tend to concentrate on the gap between the ends of the permanent magnets located on the forward side of.

5 to 7 show an example of magnetic field analysis. The magnetic field analysis shown in FIG. 5 is for the magnetic flux only by the permanent magnet 8. Further, the magnetic field analysis shown in FIG. 6 regards the permanent magnet position as the magnetic air gap 8c, and is for the magnetic flux generated by the winding 10 of the stator 2. Furthermore, FIG.
The magnetic field analysis shown in (1) is for the combined magnetic flux of the permanent magnet 8 and the winding 10.

Here, the gap portion 3b at the end of the permanent magnet located on the forward side of the rotor rotating in the direction indicated by R in FIG.
Magnetic field lines are dense in. The blank portion indicated by 5 in FIG. 7 is a space sandwiched between the teeth 4.

The concentration of the magnetic flux causes an increase in iron loss and causes heat generation in the rotor body 3a, and there is a problem that the efficiency of the motor is reduced.

Further, in the structure of the above-mentioned prior invention, since the permanent magnets are arranged in two layers with a space therebetween so as to be substantially parallel to each other, the two permanent magnets 8a, 8b with respect to the rotor surface are arranged.
The amount of magnetic flux is determined only by the surface area on the outer peripheral surface side of the permanent magnet 8a located substantially on the outer peripheral side of the rotor body 3a, and the magnet torque at both ends of the permanent magnet 8b located on the inner side cannot be effectively used. Had.

Therefore, there is a demand for a structure in which the density of the magnetic flux generated in the gap portion 3b at the end portion of the permanent magnet located on the forward side in the rotating direction R can be alleviated and the efficiency of the motor can be improved.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and to provide a rotor with a permanent magnet which can reduce the magnetic flux density at a specific location and can efficiently utilize magnet torque and reluctance torque.

[0012]

In order to solve the problems of the above-mentioned prior invention, the present invention is arranged in a rotor body made of a high magnetic permeability material with two or more layers per pole in the radial direction of the rotor. In a rotor in which a plurality of pairs of permanent magnets are embedded, the spacing between the permanent magnets in a layer relationship is wider at least on the end side of the rotor in the rotation direction than at the other end. It is characterized in that it is configured as follows.

Further, it is preferable that each of the permanent magnets arranged in two layers is formed in an arc shape which is convex in the centripetal direction of the rotor.

Further, according to the present invention, in order to solve the above-mentioned problems of the prior invention, in the rotor, the center of curvature of the permanent magnet located on the inner peripheral side of the rotor is determined from the center of curvature of the permanent magnet located on the outer peripheral side of the rotor. It is characterized in that it is provided so as to be located on the centrifugal side, and the gap between both ends of the permanent magnets in a layer relationship is formed wide.

[0015]

The present invention having the above-described structure can perform the following operations. That is, since the spacing between the permanent magnets in the above layer relationship is configured such that the spacing on the end side located at least on the forward side in the rotation direction of the rotor is wider than the spacing on other portions, The interval on the advancing side of the rotor is expanded, and it is possible to reduce the concentration of magnetic flux generated at the position of the interval on the advancing side of the rotor rotating in the expanded direction. Further, if each permanent magnet embedded in two layers is formed in a circular arc shape that is convex in the centripetal direction of the rotor,
Since the magnetic flux related to the reluctance torque is smoothly guided between the permanent magnets along the convex arc, the magnetic resistance related to the magnetic path formation is reduced and the motor efficiency can be improved.

Further, the permanent magnets located on the inner circumference side of the rotor are provided so that the center of curvature of the permanent magnets are located on the centrifugal side of the rotor from the center of curvature of the permanent magnets located on the outer circumference side of the rotor. As long as the gap between both ends is wide, whether the motor is rotated forward or reverse, the gap on the forward side of the rotor will be wide, and the concentration of magnetic flux in this part will be alleviated. The same operation as described above can be performed. Further, the curvature center point of the permanent magnet having a multilayer structure is defined by claim 3.
If set as described in (1), not only the surface area of the permanent magnet located on the outer peripheral side but also the surface area of both ends of the permanent magnet located on the inner peripheral side are added, and these are effectively utilized magnetically. Therefore, there is an effect of increasing the amount of magnetic flux on the rotor surface, and the magnet torque can be effectively used.

[0017]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention.

The rotor 3 is arranged in the rotor body 3a made of iron at a distance of 2 layers per pole in the radial direction of the rotor.
.. are embedded, and the permanent magnets 8a, 8b of each set are arranged adjacent to each other so that the S poles and the N poles alternate, and are in a layer relationship. , 8b
Is configured so that the polarities on the outer peripheral side are the same. The outer permanent magnets 8a, ... And the inner permanent magnet 8
Each of b, ... Is formed in an arc shape that is convex in the centripetal direction of the rotor.

Further, the spacing 3b on the end side of the permanent magnet 8 having the above-mentioned layer relationship, which is located on the advancing side of the rotor 3 in the rotation direction R.
Are formed wider than the intervals of other parts. That is, when the rotor 3 rotates in the R direction shown in FIG. 1, the end portions 9a, 9b of the permanent magnets 8a, 8b on the forward side thereof have a wide gap 3b as shown by W in the figure and the other end. The part interval has a width smaller than W as shown by x in the figure.

On the other hand, a plurality of teeth 4 are provided on the stator 2 side.
Is provided and a winding 10 is arranged between these teeth 4, and a rotating magnetic field is generated by applying a current to the group of windings 10.

In the above structure, the rotor 3 has the winding 1
The rotor main body 3a covered with an iron material of a high magnetic permeability material which receives a rotating magnetic field generated by the group 0 and a magnetic flux easily passes through, and a permanent magnet 8 (8a, 8b) of a low magnetic permeability material which does not easily pass a magnetic flux. . Then, as shown in FIG. 1, each set of permanent magnets 8
The inductance is different between the d-axis direction, which is the radial direction passing through the center of, and the q-axis direction, whose electrical angle is orthogonal to that direction.

In such a structure, in the d-axis direction in FIG. 1, the magnetic flux generated by the winding group 10 does not pass and the inductance can be made extremely small, while in the q-axis direction where the electrical angle is orthogonal to the d-axis. , Inner and outer permanent magnets 8b, 8
A magnetic path in the direction indicated by p in the figure is formed in the interval portion of a so that the magnetic flux can easily pass therethrough and the inductance becomes large, whereby the reluctance torque is effectively used. A magnetic path is also formed in the direction indicated by Pa in the figure.

When the rotor 3 rotates in the direction indicated by R in FIG. 1, the magnetic flux in the prior art shown in FIG. 4 causes the gap 3b between the end portions 9a, 9b of the permanent magnets 8a, 8b located on the forward side in the rotational direction ( In the width x), the magnetic flux was dense and easily saturated, but in the present embodiment, the gap between the end positions 9a and 9b of the permanent magnets 8a and 8b located on the forward side in the rotation direction R is determined. Since 3b is provided wide as shown by W in FIG. 1, it is possible to reduce the concentration of magnetic flux in the interval 3b.

In the above embodiment, the rotational position and the rotational frequency of the rotor portion 3 are detected in advance by the hall element or the encoder, and the current flowing through the winding 10 group of the stator 2 is the reluctance torque or the magnet torque. In order to obtain a large value, the current phase is shifted so that the current value has a peak at a position slightly deviated from the q-axis, and an alternating current having a frequency corresponding to the rotor rotation speed is supplied.

Next, a second embodiment of the present invention will be described with reference to FIGS.

In the second embodiment, of the arc-shaped permanent magnets 8 arranged in two layers of the first embodiment, the center of curvature Rb of the permanent magnet 8b located on the inner circumference side of the rotor is located on the outer circumference side of the rotor. The permanent magnets 8a and 8b are provided so as to be located on the rotor centrifugal side from the curvature center point Ra of the permanent magnet 8a and have a layer relationship.
It is characterized in that the gaps 3b, 3b between the both ends 9a, 9b are formed to have a wide width W. Since the other structures of the second embodiment are the same as those of the first embodiment, common parts are denoted by the same reference numerals in FIG. 2 and detailed description thereof is omitted.

In the rotor 3 constructed as described above, even if the rotor 3 rotates in the normal direction or the reverse direction, the gap 3b between the end positions 9a and 9b of the permanent magnets 8a and 8b located on the forward side in the rotation direction R becomes wide W, As in the first embodiment, it is possible to reduce the concentration of magnetic flux in the space 3b.

Further, as shown in FIG. 3 (a), the permanent magnet 8b located inside can generate a large amount of magnetic flux with respect to the rotor surface by the shaded portions 9c and 9d.

That is, the magnetic flux N of the permanent magnet 8a located on the rotor surface side shown in FIG. 3 (b) is backed up by the magnetic flux N of the central portion of the permanent magnet 8b having the same surface area as the permanent magnet 8a located on the back side thereof. Meanwhile, the permanent magnet 8
The magnetic flux of both ends 9c and 9d of b directly reaches the surface of the rotor 3. Therefore, as shown in FIG. 3C, on the surface of the rotor 3, the magnetic flux generated by the permanent magnet 8a and 9c, 9d
The sum of the magnetic flux and the magnetic flux is output. By thus increasing the effective surface area of the permanent magnet 8 and further increasing the amount of magnetic flux, a strong magnet torque can be obtained.

In the above embodiment, four sets of permanent magnets 8 are used.
Although an example using a and 8b is shown, other numbers of sets may be used. Further, the shape of the permanent magnet 8 is not limited to the arc shape which is convex in the centripetal direction of the rotor. In the above embodiment, the permanent magnets 8a and 8b are all made of permanent magnets up to the ends 9a and 9b, but the ends 9a and 9b are made of voids (air layers) or synthetic resin layers. You may. That is, the present invention is not limited to the above embodiments, and various modifications can be made based on the spirit of the present invention, and these modifications are not excluded from the scope of the present invention.

[0032]

According to the present invention, in a rotor having a permanent magnet of a multi-layer structure, it is possible to reduce the magnetic flux density at a specific location, reduce iron loss, and efficiently generate magnet torque and reluctance torque. By utilizing this, it is possible to provide a rotor with a permanent magnet that rotates with high efficiency.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention.

FIG. 2 is a partial sectional view showing a second embodiment of the present invention.

FIG. 3 shows the principle of (a),
(B) and (c) are conceptual diagrams.

FIG. 4 is a sectional view showing the prior invention.

FIG. 5 is a diagram showing a magnetic field analysis result of magnetic flux by a permanent magnet.

FIG. 6 is a diagram showing a magnetic field analysis result of magnetic flux generated by a winding group.

FIG. 7 is a diagram showing a magnetic field analysis result of a synthetic magnetic flux generated by a permanent magnet and a winding group.

[Explanation of symbols]

 2 stator 3 rotor 3a rotor body 3b end side spacing 4 teeth 8, 8a, 8b permanent magnets 9a, 9b end 10 windings

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Ito 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Masayuki Jinto 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. 72) Inventor Yoshinari Asano 1006 Kadoma, Kadoma City, Osaka Prefecture, Matsushita Electric Industrial Co., Ltd. (72) Naoyuki Sumiya, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (3)

[Claims] 1. A rotor body comprising a rotor body made of a high magnetic permeability material, and a plurality of sets of permanent magnets arranged at intervals of two layers or more per pole in the rotor radial direction. A rotor with permanent magnets, characterized in that a gap between certain permanent magnets is configured such that a gap on an end side located at least on a forward side in a rotation direction of the rotor is wider than a gap on other portions. 2. The permanent magnets arranged in two layers are formed in an arc shape which is convex in the centripetal direction of the rotor.
The described rotor with a permanent magnet. 3. A rotor main body made of a high magnetic permeability material, in which a plurality of sets of permanent magnets are embedded in a rotor body in a radial direction of the rotor at intervals of two or more layers. The center of curvature of the permanent magnet located on the side of the rotor is located closer to the centrifugal side of the rotor than the center of curvature of the permanent magnet located on the outer peripheral side of the rotor, and the gap between the both ends of the permanent magnet in the layer relationship is widened. Rotor with permanent magnet.